Device for crimping multifilament threads

ABSTRACT

A technique for crimping multifilament threads involves a device having an injector installation and having a stuffing installation. The injector installation has a conveying duct having a thread inlet. The conveying duct of the injector installation opens into a stuffer chamber of the stuffing installation. The stuffer chamber in an upper chamber portion, between a plurality of wall portions of a chamber wall, has a plurality of slot-shaped air-exhaust openings. The wall portions of the chamber wall, in order to configure the air-exhaust openings, each have one flow edge which is aligned so as to be tangential to a chamber circle.

The invention relates to a device for crimping multifilament threads according to the preamble of claim 1.

A device of the generic type for crimping multifilament threads is known from EP 0 784 109 B1.

Devices of this type for crimping multifilament threads are usually employed in a melt-spinning process so as to continuously produce crimping on a multifilament synthetic thread. To this end, the device has an injector installation and a stuffing installation which in the running direction of the thread are disposed in sequence. In this way, the injector installation has a conveying duct having a thread inlet, in order for the thread to be guided by means of an air stream into the contiguous stuffing installation. The stuffing installation has a stuffer chamber for receiving the thread, wherein the thread within the stuffer chamber is congested such that the individual filaments within the stuffer chamber are deposited in loops and arcs so as to form a thread plug. It is required here that the air stream utilized for conveying is diverted in an upper chamber portion of the stuffer chamber. To this end, a plurality of air-exhaust openings which extend in a slot-shaped manner between individual fins are formed in the upper chamber portion. It is usual here for the fins to be disposed in a radial manner or in parallel beside one another, depending on the cross section of the stuffer chamber. The air stream utilized for conveying the thread may thus be laterally diverted out of the stuffer chamber. Here, the fundamental issue arises that individual filaments to a greater or lesser extent are released from the plug composite and are pulled into the air-exhaust openings. Thus, interlocking and breaking of filaments cannot be excluded.

However, other solutions in which the air-exhaust openings are formed by bores in a chamber wall of the stuffer chamber are also known in the prior art. For example, a device of this type for crimping multifilament threads is described in EP 1 116 806 A1. By virtue of the fineness of the filaments, it cannot be avoided even here that individual filaments are drawn in by the air stream. Indeed, the bore diameter may be minimized within certain limits, this however leading to a greater investment in production and, in particular, to increased susceptibility to contamination. However, as contamination increases, the ventilation of the stuffer chamber deteriorates as the operational time progresses.

It is now an object of the invention to provide a device of the generic type for crimping multifilament threads, in which ventilating the stuffer chamber is capable of being carried out in a manner particularly gentle to the threads.

This object is achieved according to the invention in that the wall portions of the stuffer chamber, in order to configure the air-exhaust openings, each have one flow edge which is aligned so as to be tangential to a chamber circle.

Advantageous refinements of the invention are defined by the features and combination of features of the respective dependent claims.

The invention has the particular advantage that no radial flow outward from the center of the stuffer chamber may be formed. A deflection of the air stream on the flow casing into the air-exhaust openings is required independently of the point at which the air stream impacts the stuffer-chamber wall. However, a deflection of this type of the air stream impedes the entrainment of individual filaments. The forced deflection of flow by the flow edges of the wall portions enables ventilation of the stuffer chamber at a low tendency toward filaments being drawn into the air-exhaust openings.

In order for a uniform air stream from the inside to the outside to be obtained across the entire chamber cross section of the stuffer chamber, the refinement of the invention is preferably embodied in which the flow edges of the wall portions, based on a diameter of the chamber circle, are configured so as to be symmetrical in a mutually adjacent manner. The chamber circle is a geometric auxiliary parameter used for assigning a geometric definition to the arrangement of the flow edges of the wall portions.

The chamber circle, in order to align the wall portions, in terms of diameter can be chosen so as to be smaller than or equal to a cross-sectional envelope of the stuffer chamber. The larger the chamber circle gets in relation to the cross-sectional envelope of the stuffer chamber, the larger a deflection angle for deflecting the air stream gets. The theoretical maximum angle is achieved when the diameter of the chamber circle at which the flow edges are aligned approximates a nominal diameter of the stuffer-chamber cross section.

In order for the air-exhaust openings to be manufactured, the refinement of the invention is particularly advantageous in which the wall portions of the stuffer chamber are formed by a plurality of fins, wherein the flow edges are formed on internal sides of the fins and wherein the air-exhaust openings each extend between two adjacent fins. Thus, slot-shaped air-exhaust openings result, which extend substantially across the length of the fins.

In order for the thread plug to be produced, the refinement is preferably utilized in which the fins, so as to from a round chamber cross section of the stuffer chamber, are disposed beside one another in an overlapping manner. The filaments of a thread may thus be deposited on the surface of the thread plug in a particularly uniform manner.

In order to obtain uniform ventilation across the entire cross section in the case of a low number of fins and, related thereto, a low number of air-exhaust openings, the refinement of the invention is provided in which the fins in an internal wall region have a plurality of bores which open into an air-exhaust duct. These bores act as additional vents on the lateral face of the fins, which divert the air from the stuffer chamber.

The effect of flow deflection when ventilating the stuffer chamber may yet be advantageously facilitated in that the injector installation has a compressed-air supply which in the conveying duct produces a swirl flow. It has already been demonstrated in this way in the case of conventional radial arrangements of wall portions that a swirl flow reduces the tendency of the filaments to be drawn into the air-exhaust openings when the thread is deposited into a thread plug.

In particular in the case of the injector installation and the arrangement of the wall portions of the stuffer chamber being adapted to one another in such a manner that a rotational direction of the swirl flow counteracts an exhaust flow which exits through the air-exhaust opening, a pronounced deflection of the flow is effected when the stuffer chamber is ventilated.

The device according to the invention is fundamentally suitable for producing crimping in a multifilament yarn independently of the type of polymer and of the thread count. In this way, the device may be used both in a single-stage as well as in a multi-stage manufacturing process for crimped yarns.

The invention will be explained in more detail hereunder by means of a few exemplary embodiments of the device according to the invention, with reference to the appended figures in which:

FIG. 1 schematically shows a longitudinal sectional view of a first exemplary embodiment of the device according to the invention;

FIG. 2 schematically shows a cross section of the stuffer chamber of the exemplary embodiment as per FIG. 1;

FIG. 3 schematically shows a longitudinal sectional view of a further exemplary embodiment of the device according to the invention;

FIG. 4 schematically shows a cross section of the stuffer chamber of the exemplary embodiment of FIG. 3;

FIG. 5 schematically shows a plurality of views of a stuffer-chamber ventilation.

A first exemplary embodiment of the device according to the invention is schematically shown in a plurality of views in FIGS. 1 and 2. The exemplary embodiment is shown in a longitudinal sectional view in FIG. 1, and in a cross-sectional view in FIG. 2. To the extent of there being no explicit reference to any of the figures, the following description applies to both figures.

As can be derived from the illustration in FIG. 1, the device according to the invention for crimping multifilament threads has an injector installation 1 and a stuffing installation 8, preferably formed as a common structural unit. The injector installation 1 has a nozzle body 22 having a conveying duct 3 which is disposed so as to be substantially centric and which at a free end of the nozzle body 22 forms a thread inlet 4. At the opposite end the conveying duct 3 opens into a stuffer chamber 9 of the stuffing installation 8.

The conveying duct 3 is assigned a compressed-air supply 2 through which preferably heated compressed air is introduced into the conveying duct 3. The compressed-air supply 2 is formed by a compressed-air connector 7, a compressed-air duct 6, and at least two injector bores 5.1 and 5.2. The injector bores 5.1 and 5.2 open into the conveying duct 3 in such a mutually offset manner that compressed air which is introduced into the injector bores 5.1 and 5.2 by way of the compressed-air duct 6 within the conveying duct 3 leads to a swirl flow.

During operation, a multifilament thread is suctioned into the conveying duct 3 by the vacuum effect produced at the thread inlet 4 and led to the stuffing installation 8 by means of the swirled air stream.

The stuffing installation 8 in this exemplary embodiment is formed by a stuffer chamber 9 which has an upper chamber portion 10.1 and a lower chamber portion 10.2.

In order for the upper chamber portion 10.1 of the stuffer chamber 9 to be explained, reference is additionally made to the illustration in FIG. 2. As can be derived from the illustrations in FIGS. 1 and 2, the upper chamber portion 10.1 has a plurality of fins 14, which in an imbricated arrangement form a round chamber cross section of the stuffer chamber 9. The fins 14, by way of an internal side forming a flow edge 21, are each aligned so as to be tangential to a chamber circle 16, and between them form in each case one slot-shaped air-exhaust opening 13. The flow edges 21 of the fins 14, based on a diameter of the chamber circle 16, are symmetrically disposed and aligned in an overlapping manner. The air-exhaust openings 13 which extend between the fins 14 open into tangentially aligned exhaust ducts 23, penetrating in a slot-shaped manner the one chamber wall 11 formed by the fins 14 from the inside to the outside.

The diameter of the chamber circle 16 in FIG. 2 is referenced with the capital letter D. In this exemplary embodiment, a chamber circle diameter has been chosen which is smaller than a cross-sectional envelope of the stuffer chamber 9. In principle, the angular positioning of the fins 14, and the number of fins 14, and thus the chosen chamber circle diameter, is illustrated in an exemplary manner only.

In order for the chamber wall 11 to be formed, the fins 14 are held by a fin support 15.

As can be derived in particular from FIG. 1, the fin support 15 is embodied in two parts and interacts with a housing 18. The housing 18 encloses the fins 14 in a spaced-apart manner, so as to be able to receive air exiting from the chamber portion 10.1 of the stuffer chamber 9. The housing 18 has ventilation openings or ventilation connectors (both not illustrated here) for discharging the spent air.

As can be further derived from the illustration in FIG. 1, the free ends of the fins 14 lead into the lower chamber portion 10.2 of the stuffer chamber 9. The lower chamber portion 10.2 of the stuffer chamber is formed in a duct-shaped manner in a guide body 24, and is limited by a chamber outlet (not illustrated here).

During operation, a multifilament thread is conveyed by way of the conveying duct 3 of the injector installation 1 into the stuffer chamber 9 of the stuffing installation 8. At the start of the process, the stuffer chamber 9 is briefly closed off such that a thread plug is configured within the stuffer chamber 9. The thread plug fills the entire chamber cross section of the stuffer chamber 9, wherein the formation of the thread plug commencing in the upper chamber portion 10.1. In order for the conveying air of the thread from the injector installation 1 to not lead to the thread plug being blown out, the conveying air in the upper chamber portion 10.1 of the stuffer chamber 9 is laterally discharged by way of the air-exhaust openings 13 and the exhaust ducts 23 between the fins 14.

Guiding of air for ventilating the stuffer chamber is schematically indicated by flow arrows between adjacent fins 14 in FIG. 2. The air stream entering into the stuffer chamber 9 here has a direction of swirl which is in the clockwise direction. The exhaust air flow which is produced by the exhaust-air opening 13 is counter to the direction of swirl such that a deflection of flow arises when the air stream impacts on the flow edge 21. Thus, air streams which are directed directly from the inside to the outside can be advantageously avoided. Drawing in of individual filaments is advantageously substantially impeded by the deflection of flow at the flow edges 21 of the fins 14. A substantially more stable and uniform crimping of the filaments has been able to be achieved therewith. Fraying of the thread plug within the stuffer chamber is avoided.

In the exemplary embodiment illustrated in FIGS. 1 and 2, the number of the fins, the shape of the fins, and the angular arrangement of the fins is illustrated in an exemplary manner. It is essential here that the air-exhaust openings and exhaust ducts by way of the flow edges within the chamber wall 11 have a tangential alignment in order to deflect the blowing flow. Likewise, the cross section of the stuffer chamber 9 does not mandatorily have to be round. In this way, oval or angular cross sections are also possible. A reduction in the number of fins would reduce the cost of the stuffing installation, in particular. For example, a minimum of three fins which are mutually arranged in a triangular shape could form a ventilation portion of the stuffer chamber. Likewise, non-uniform arrangements of the fins are also possible, the tangential alignment thereof being defined by different chamber-circle diameters.

A further exemplary embodiment of the device according to the invention for crimping multifilament threads is illustrated in a plurality of views in FIGS. 3 and 4. A longitudinal sectional view is schematically shown in FIG. 3, and a cross-sectional view of the stuffer chamber is shown in FIG. 2. The exemplary embodiment as per FIGS. 3 and 4 is substantially identical to the exemplary embodiment as per FIGS. 1 and 2 such that only the points of difference will be explained hereunder, reference otherwise being made to the aforementioned description.

As opposed to the aforementioned exemplary embodiment, the chamber wall 11 of the upper chamber portion 10.1 of the stuffer chamber 9 is formed by a low number of fins 14.

As can be derived in particular from the illustration in FIG. 4, the tangential alignment of the flow edges 21 of the fins 14 is determined by a chamber circle 16 which in terms of the diameter thereof is substantially equal to a cross-sectional envelope of the stuffer chamber 9. This results in an extreme position of the fins 14, requiring the greatest possible deflection of the air stream on the flow edges 21.

By virtue of the low number of fins 14 for forming the chamber wall 11, correspondingly few air-exhaust openings 13 are configured so as to be distributed across the chamber cross section. In order for intensive ventilation of the stuffer chamber 9 to nevertheless be obtained, the fins 14 have a plurality of bores 17 in an internal wall region. As can be seen in particular in the illustration of FIG. 4, the flow edge 21 forms a delimitation of the stuffer chamber 9 such that the bores 17 contained therein directly contribute toward ventilating the stuffer chamber 9. The bores 17 in the fins 14 open into a exhaust duct 23 which extends between adjacent fins 14 and connects the air-exhaust opening 13 to an environment.

Functioning of the exemplary embodiment as per FIGS. 3 and 4 is identical to that of the aforementioned exemplary embodiment such that reference is made at this point to the aforementioned description.

In the exemplary embodiments as per FIGS. 1 to 4, the upper chamber portion 10.1 of the stuffer chamber 9 within the stuffing installation 8 is formed by a plurality of individual fins 14 which are arranged beside one another and in an overlapping manner so as to form a chamber wall 11. In principle, however, there is also the potential for the chamber portion 10.1 of the stuffer chamber 9 to be formed by a ventilation body.

An exemplary embodiment of a ventilation body 19, such as would be employable for example in the exemplary embodiment as per FIGS. 1 and 2, in order for the upper chamber portion 10.1 of the stuffer chamber 9 to be formed, is illustrated in FIGS. 5.1 and 5.2. The ventilation body 19 is illustrated in a side view in FIG. 5.1, and in a cross-sectional view in FIG. 5.2. The following description applies to either figure unless explicit reference is made to a specific one of the figures.

The ventilation body 19 is cylindrically configured, enclosing an internal chamber portion 10.1 of a stuffer chamber 9. The chamber wall 11 is subdivided by a plurality of axially running separation slots 20 into a plurality of wall portions 12.

As can be derived in particular from FIG. 5.2, the separation slots 20 penetrate the chamber wall 11 in such a manner that the wall portions 12, in order to form air-exhaust openings 13, each have a flow edge 21 which is aligned so as to be tangential to a chamber circle 16. The flow edges 21 formed by the wall portions 12 thus effect on the air-exhaust openings 13 a deflection of the exhaust flow exiting from the interior of the stuffer chamber 9. As can be derived from the illustration in FIG. 5.1, the separation slots 20 on an inlet side 25 of the ventilation body 19 are delimited such that the separation of the chamber wall 11 into a plurality of wall portions 12 is restricted to a partial length of the ventilation body 19.

The invention thus also extends to stuffing installations of which the upper chamber portion of the stuffer chamber is formed from a ventilation body having a corresponding configuration of wall portions, or from a plurality of fins.

The devices illustrated in the exemplary embodiments may advantageously be employed for crimping multifilament yarns. Here, multifilament threads may be crimped directly in a melt-spinning process or in a multi-stage manufacturing process. 

1. Device for crimping multifilament threads, having an injector installation and having a stuffing installation, wherein the injector installation has a conveying duct having a thread inlet, wherein the conveying duct of the injector installation opens into a stuffer chamber of the stuffing installation, wherein the stuffer chamber in an upper chamber portion, between a plurality of wall portions of a chamber wall, has a plurality of slot-shaped air-exhaust openings, and wherein the wall portions of the chamber wall, in order to configure the air-exhaust openings, each have one flow edge which is aligned so as to be tangential to a chamber circle.
 2. Device as claimed in claim 1, wherein the flow edges of the wall portions, based on a diameter of the chamber circle, are configured so as to be symmetrical in a mutually adjacent manner.
 3. Device as claimed in claim 1, wherein the chamber circle, in order to align the flow edges, in terms of diameter is chosen so as to be smaller than or equal to a cross-sectional envelope of the stuffer chamber.
 4. Device as claimed in claim 1, wherein the wall portions of the chamber wall are formed by a plurality of fins, wherein the flow edges are formed on internal sides of the fins and wherein the air-exhaust openings each extend between two adjacent fins.
 5. Device as claimed in claim 4, wherein the fins, so as to form a round chamber cross section of the stuffer chamber, are disposed beside one another in an overlapping manner.
 6. Device as claimed in claim 4, wherein the fins in an internal wall region have a plurality of bores which open into an air-exhaust duct.
 7. Device as claimed in claim 1, wherein the fins are disposed on a support, wherein the free ends of the fins lead into a lower chamber portion of the stuffer chamber.
 8. Device as claimed in claim 1, wherein the injector installation has a compressed-air supply which in the conveying duct produces a swirl flow.
 9. Device as claimed in claim 8, wherein the injector installation and the arrangement of the wall portions of the stuffer chamber are adapted to one another in such a manner that a rotational direction of the swirl flow counteracts an exhaust flow which exits through the air-exhaust openings.
 10. Device for crimping multifilament threads, the device comprising: an injector mechanism that includes a conveying duct having a thread inlet, and a stuffing mechanism that includes a stuffer chamber having a chamber wall, wherein the conveying duct of the injector mechanism opens into the stuffer chamber of the stuffing mechanism, wherein the stuffer chamber in an upper chamber portion, between a plurality of wall portions of the chamber wall, has a plurality of slot-shaped air-exhaust openings, and wherein the wall portions of the chamber wall, to configure the air-exhaust openings, each have one flow edge which is aligned so as to be tangential to a chamber circle. 